Truing apparatus for abrading machines



Jan. 27, 1942. |NDGE 2,271,013

TRUING APPARATUS FOR ABRADING MACHINES Original Filed Feb. 6, 1955 s Sheets-Sheet 1 lag-5 3 371 371a 5/ E 37058 0a 2 52 0 t 50 l- I98 lea l6! I77 197 200 62 I80 1 I .5

HERBER T 5. INDG'E attorney Jan. 27, 1942. H. s. INDGE 2,271,013

TRUING APPARATUS FOR ABRADING MACHINES Original Filed Feb. 6, 1935 5 Sheets-Sheet 3 F 3 24-6 3nventor HERBERT 5. INDG'E I (Ittorneg Jan. 27, 1942. H. s. INDGE 2,271,013

TRUING APPARATUS FOR ABRADING MACHINES Original Filed Feb. 6, 1935 5 Sheets-Sheet 4 Fi .1] H910 Zhwentor HERBERT 5'. INDGE Jan. 27, 1942. H. s. INDGE TRUING APPARATUS FOR ABRADING MACHINES Original Filed Feb. 6, 1935 5 Sheets-Sheet 5 llll'll Snnentor in Rm 9 R. B

, tlnuous lapping machine.

. Patented Jan. 27, 1942 raumc APPARATUS roa ammo MACHINE Herbert S. Indie, Westboro, Mass, assignor to Norton Company, Worcester, Mass, at corporation of Massachusetts Original application February 6, 1935, Serial No. 5,271, now Patent No. 2,087,874, dated July 20,

1937, Serial No. 132,753

Claims.

The invention relates to truing apparatus for abrading machines, and with regard to its more specific features to truing apparatus for a lapping machine. This is a division of my copending application Serial No. 5,271 filed February 6, 1935, which matured as Patent No. 2,087,874 July 20,

One object of the invention is to provide a con- Another object of the invention is to provide an efficient abrader adapted to turn out a large quantity of work pieces finished to within close tolerances in a short period of time. Another object of the invention is to provide an abrader mechanism susceptible of embodiment in a, rugged machine adapted for operation on different sized work pieces and characterized by simplicity of structure and ease of adjustment. Another object of the invention is to provide, in an abrader, mechanism for quickly reshaping an abradant element to suit it to a particular size of work piece or to resurface it. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, and in the several steps and relation or order of each of said steps to one or more of the others thereof, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of various possible embodiments of the mechanical features of this invention,

Figure 1 is a front elevation of a continuous lapping machine constructed according to the invention;

Figure 2 is an end view of the machine, looking from the right in Figure 1;

Figure 3 is a plan view of the machine with the column shown in cross-section and the upper cone removed;

Figure 4 is a detail view, partly in front elevation and partly in section, of a driving and controlling apparatus for a dressing carriage;

Figure 5 is a cross-sectional view taken on the line 5--5 of Figure 4;

Figure 6 is a sectional' view taken on the line 66 of Figure 1. illustfi'ating details of the work guide adjusting structure;

Figure '7 is a view similar to Figure 6, the section plane being indicated by the line I-l in Figure 1, and illustrating the other end of the work guide adjusting structure;

Figure 8 is a fragmentary view showing the Divided and this application March 24,

work feeding'trough and its support at the righthand side of the machine;

Figure 9 is a view of the outer end of the work feeding trough and support, looking in the direction of the arrows 9-9 in Figure 8;

Figure 10 is an end elevation of the dressing wheel and truing instrumentality therefor;

Figures 11 and 12 are views of the dressing wheel and truing instrumentality therefor from different positions;

Figure 13 is a fragmentary view showing a device for setting the truing instrumentality for the dressing wheel;

Figure 14 is a sectional view taken along the lines 14- of Figure 12, looking in the direction of the arrows;

Figure 15 is a horizontal sectional view of the driving and controlling apparatus for the dressing carriage;

Figure 16 is a view partly in front elevation and partly in vertical section of the work guide structure on an enlarged scale;

Figure 17 is a plan view of the work guide structure on an enlarged scale;

Figure 18 is a fragmentary sectional view of the work guide and feeding devices; Figures 19, 20, 21 and 22 are cross-sectional views taken on the lines indicated by the corresponding numerals and looking in the direction of the arrows as shown on Figure 16.

Referring first to Figure 1, I provide a support or base of sufficient size and strength to provide a firm foundation for the machine elements. Referring now to Figure 3, uprising from the base P 20 and suitably secured thereto or integrally formed therewith is a column 2| which has vertical ways 22 and 23. A vertically movable slide 24 has ways 25 and 26 complementaryto the ways 22 and 23 respectively and thus slide 24 is mounted for vertical movement, and the area of the surfaces on the severalways is suillcient to hold the slide 24 from any movement, lateral, torsional or otherwise, except vertical movement which is controlled as hereinafter described.

Referring now to Figures 1 and 2, rigidly secured to the base 20 in front of the column 2| is a supporting plate 28. This plate 28 has a milled or planed horizontal upper surface 29 upon which rests a table 30. A trunnion 3i having a vertical axis extendsvdownwardly from the under side of the table 30 and fits in a bore 32 in the supporting plate 28, and thus the table 30 is restrained against any horizontal movement on the plate 28 except an oscillating or angular movement.

The weight of the machine parts and the broad surface 28 of the plate 28 and the cooperating under surface of the table 38 secures the table '38 against any vertical movement or strain, while up structure comprising a plurality of strictly -frusto-conical portions 5|, the large diameter of each being the same as the small diameter of the next, except for the final largest cone, this builtup structure being clearly identified in Figure 1, and all the frusto-conical portions 5| having a central bore for mounting upon theshaft 48. Any suitable cement may be used to secure the several frusto-conical bodies 5| together, and the entire cone may be clamped in position between end plates 52 and 53 prior to the mounting of the of the machine is a head 38. This head 38 may,

if desired, be integral with the table-38 or may otherwise be rigidly attached thereto. Provided in the head 38 are a pair of bearing surfaces having the same horizontal axis for the support of a shaft 48, there being a worm wheel 4| secured to the shaft 48 and located between the bearing surfaces and received in a cut-out portion of the head 38, 'as is best shown in Figure 2. The head 38 also has a pair of coaxial bearing surfaces for the support of a shaft whose axis is perpendicular to the axis of the shaft 48. A worm 44 located in the cut-out portion of the head 38 meshes with the worm wheel 4| and thus the shaft 48 may be driven from the shaft 43, the

a drive of the latter being hereinafter described.

Referring now to Figures 1 and 7, the lefthand end of the shaft 48 is supported in a horizontal bearing provided in a head 48. The head 48 has on its under surface dovetailed ways '41 cooperating with similar ways 48 provided on a plate 49 upstanding from and attached to table 38. The head 48 is removable as a unit from the table 38, and thus it is that the shaft 48 to which is secured a lapping cone to be described may be mounted inand extend between the heads 38 and 48. These heads provide not only the radial bearing surfaces mentioned but also longitudinal thrust bearing surfaces, and when, in the assembly of the machine or after replacement of the lower lapping cone, the head 48 is brought to the desired position of adjustment on the ways 48 it may be clamped in position by any suitable holding or clamping bolts, not shown, and when so fixed to the table 38 it need not again be disturbed unless or until it is desired to replace the lower lapping cone with a new one, or wear in the parts makes some adjustment desirable. Thus it is that the lower lapping cone 58 is mounted on a horizontal axis for rotation and is fixed in position except that it may be angularly adjusted to cause its axis to assume any desired angle with the front face of the machine, within limits, and always in a horizontal plane.

Considering now the lower lapping cone 58, it is preferably made of abrasive material. The exact abrasive, grain size, grade, structure and bond of the cone 58 will be selected for the work which a particular machine according to the invention is to perform, but specifically with respect to the lapping of small rolls or sleeves, for

example wrist pins for assembly into intemalcombustion engine pistons, a fine grain in a shellac bond and a dense structure are characteristics whereby excellent results in practice may be achieved. In order to avoid internal strains and stresses and in order to facilitate the manufacture of the lapping cones forming part of the machine, I prefer to embody them in a builtwhole unit, including cone 58 and shaft 48 in position between the heads 38 and 48 as already described. As indicated in the drawings, the cone axis is the same as the axis of the shaft 48, and I note that preferably the axis of the trunnion 3| not only intersects the cone axis but also bisects it, the cone 58 being strictly geometrically speaking a frusto'cone and its axisbeing considered as limited by its plane end surfaces. The'present description of the cones is before they are dressed.

Still referring to Figure 1, above the cone 58 is a second or upper lapping cone 55. This upper cone 55 is preferably of the same size as the cone 58, and is mounted on the slide 24 in a manner similar to the mounting of the cone 58 on the table'38. It is noted that the small end of the cone 55 is opposite the large end of the cone 58, and furthermore, apart from the special wheel shaping to be hereinafter described the shape of the upper cone 55 is the same as that of the lower cone. This makes the included angle of the upper cone substantially the same as that of the lower cones and the axis of rotation of the upper cone is horizontal. It is adjustable angularly on a vertical axis which is the same as the axis of the trunnion 3| for the lower cone, so that its axis of adjustment intersects its axis of rotation and bisects it. H wever, it is movable bodily in a strictly ve ical direction, or otherwise defined in a direction perpendicular to the axes of the two cones" and along or parallel to their axes of angular djustment. Preferably the upper cone 55 is' tructurally the same as that of the cone 58, although for certain purposes the selection of abrasive, grain, grade, structure and bond might be different.

Considering now the structure in detail by which the foregoing is achieved, and referring first to Figure l, the slide 24 has a large overhanging support 58 preferably integrally formed with it and having on its under side a large fiat plane surface 51 extending approximately over the horizontal upper surface 28 of the supporting plate 28. Also against this surface 51 is a table 88, and a trunnion 8| fitting in a bore 82 mounts the table 88 for angular adjustment. The table 88 is prevented from falling and is held against the surface 51 by means of cooperating segmental guiding surfaces 83 and 84, the difference between this structure and the corresponding structure for the mounting of the table 38 being principally in the fact that, for the upper cone, it is not the surface 51 which receives the load, but rather the flanged supporting portions 85, and therefore the trunnion 8| is preferably provided with radial-supporting plates 88 to assist in supporting the load.

Extending downwardly from the table 88 at one side or end of the machine is a head 88. This head 88, like the head 38 may, if desired, be integral with the table 38 or may otherwise be rigidly attached thereto. Preferably, however,

the head 88 is opposite the head 46. Provided on the head 88 are a pair of bearing surfaces having the same horizontal axis for the support of a shaft 18, upon which is mounted the upper cone 55. A worm wheel 1| is securemto the shaft 18 and is located between the bearing surfaces and received in a cut-out portion of the head 88, as best shown in Figure 1. The head 88 also has a pair of coaxial bearing surfaces for the support of a shaft 18 whose axis is perpendicular to the axis of the shaft -18. A worm 14 located in the cut-out portion of thehead 88 meshes with the worm wheel 1| and thus the shaft 18 may be driven from the shaft 13, the drive of the latter being hereinafter described.

Referring now to Figures 1 and 2, the righthand end of the shaft 18 is supported in a horizontal bearing provided in a head 18. The head 16 h'as on its upper surface dovetailed ways 11 cooperating with similar ways 18 provided on a plate 19 extending downwardly from and attached to the table 58. The head 18, as in the case of the head 48, is removable as a unit from the table 68, thereby to permit th mounting of the shaft 18 and upper-cone 55 between the heads 88 and 18. The purpose, function and adjustment of the heads 88 and are the same as those of the heads 38 and 46. The upper cone 55 is angularly adjustable in a horizontal plane by moving table 88 on its trunnion 6| (preferably coaxial with the trunnion 3|) and in the normal operation of the machine, both -cones will be positioned so that their axes are not quite parallel to the front face of th machine (or to a given plane) by moving them out of parallelism in opposite angular directions. That is to say, the cones are skewed one with respect to the other.

Considering now the drive for the cones 58 and 55, and first with respect to the lower cone- 58, and referring particularly to Figures 2 and'3, the base 28 of the machine is provided with a flat, horizontal upper surface 88 located at the right rear portion of the machine. On this surface 88 rests a table 8| supporting an electric motor 82 whose motor shaft 83 is coupled to the shaft 43 by means of a flexible clutch coupling 84. The table 8| preferably is rigidly attached to the head 38 or forms an integral part thereof, so that the angular relation between the shafts 43 and 83 is unvarying, they being preferably exactly in line: and as the head 38 is moved in order angularly to adjust the lower cone 58, the table 8| slides upon its supporting surface 88.

Referring now to Figures 1 and 3, at the rear of the machine is a vertical fiat surface 85 on the slide 24. Attached to this is a bracket 85a having a vertical flat surface 85b on the left-hand side of the machine. To this surface 85b is bolted an electric motor 88. The motor shaft 81 of this motor is connected to the shaft 13 in order to drive the upper cone 55 by means of a couple of universal joints 88 and 89 and an intervening shaft 98. The intervening shaft 98 is a splined shaft and is keyed to one or both of the universal couplings 88 or 89. Thus the shaft 81 will drive the shaft 13 despite thev fact that they may not be in alignment nor, for difierent adjustments of the machine, the same distance apart.

For the lapping of the different sized work pieces, the cones 58 and 55 are located different distances apart. This adjustment of the machine, in this embodiment of the invention, is effected by moving the slide 24 up or down on the ways 22, 28, 25 and 28. Thereby is the upper abrasive cone moved towards or from the lower abrasive cone 58. Referring now to Figures 2 and 3, the column 2| is hollowand in this embodiment of the invention presents the appearance, in cross-section, of an equilateral triangle with a rounded apex, and is surrounded by the slide 24 which is complementary to it so that the two structures together, in cross-section, are rec-' tangular, the slide 24 being likewise hollow and.

both members having suitable ribs in the interior thereof, for the purpose of securing maximum strength and rigidity of the parts consistent with minimum weight, and one of many possible shapes and structures for these parts being better'illustrated by the drawings than is possible by way of verbal description. In the interior of the col-.

umn 2| and extending rearwardly and inwardly from the front face 9| thereof, is a pin 92. Extending forwardly and also inwardly from a transverse rib 93 in the column 2| is a pin 94 which is coaxial with the pin 92. Mounted on the two pins 92 and 94 is a collar 95 whose axis is perpendicular to the axes of the pins 92 and 94, the collar 95 being provided with journal portions at the ends of a diameter extending through its annular rim, and the collar 95 being free to move axially along the pins 92 and 94 and being, so far as these pins-are concerned, also free to move angularly on these pins.

A pin 98 perpendicular to the pins 92 and 94 extends through and is Journaled in diametrically opposite holes in the collar 95 which extend through its annular wall, and this pin 98 likewise passes through a screw shaft 91 to which it may be rigidly secured, or the pin 98 could be fast in the collar 95 but journaled in the shaft 91..

This structure thus constitutes anniversal joint between the shaft 91 and the column 2|, and also permits displacement of the shaft 91 with respect to the column 2|. From the description to be given, it will appear that the slide 24 merely rises and falls on the column 2|, being held to rectilinear movement with respect thereto by 5 means of the ways 22, 23, 25 and 26, and the shaft 91 is intended to be and preferably is parallel to these ways and consequently or from purely theoretical considerations, the shaft 91 might be merely rigidly attached to the column 2|, but precision and smoothness of operation are highly desirable in machines of this character and by the provision of the universal mounting for the shaft 91 described, a much superior drive for the vertically movable slide 24 is achieved and .one which neither chatters nor offers any more resistance to movement at one angular position of the parts than at any other. In particular, this device compensates for any slight failure to bore and thread-cut the rotatable nut along the true axis thereof to the utmost precision.

' Referring now part cularly to Figure 2, upon the top of the vertically movable slide 24 at the rear of the machine is mounted a motor I88. The motor shaft IN is connected by means of a flexible clutch coupling I82 to a shaft I83 upon which is mounted a worm I84 which meshes with a worm wheel I85 mounted on a shaft I88, upon which shaft I86 is mounted a worm |81 which meshes with a worm wheel I88, the hub of which constitutes a nut I89 whose threads fit the threads of shaft 91, the shaft 91 being mounted in the nut I89. This entire mechanism is mounted in a casing 8, III, the lower part I having a lower thrust bearing 2 for the nut I09, and the upper part IIO of the casing having an upper thrust bearing III for the nut I03, and the whole casing constituting an enclosure for retaining oil or grease for lubrication of the worms and the various journals including the thrust bearings referred to, and the upper casing IIO having Journals for the shaft I03, the Journals for the shaft I03 being between the two parts H and III of the casing. The two parts H0 and III of the casing may be secured together in any suitable manner, such as by bolts (not shown), and the casing as a whole rests upon supporting ridges I I8 provided on the lower part of the overhanging support 55, and for alignment of the casing, the lower end of the lower part III is cylindrical in form and fits in a bore II9 provided in the support 58. It will thus be seen that when the motor I00 is energized, the nut I09 will be rotated, but comparatively slowly, and this will result in moving nut I09 vertically in one direction or the other, and the motor I00 is a reversible motor and provided with suitable switches, controls and the like which need not be herein described as such are well known. Thus by suitable control of the motor I00, the slide 24 and with it the upper cone 55 may be raised or lowered, and by reason of the great reduction effected through the two pairs of worms and worm wheels, the movement of the slide is so slow that it can be brought to rest at a desired position within precision limits.

Still referring to Figure 2, in order that the operator of the machine may have a scale whereby to determine the position of the upper cone 55 and in order that he may bring it to a desired position of adjustment, I provide on the front of the machine in convenient position, and preferably at the front of the overhanging support 56, a dial scale I secured to a hand wheel I2I which is in turn fastened to a shaft I22 that may be connected to the shaft I03 by means of a disengageable clutch I23. The hand wheel I2I may also be used to raise or lower the slide 24, and particularly to lower it, since its rather considerable weight is urging it downwardly and it may easily be lowered by the hand wheel and very carefully controlled by such manual adjustment. Thus, in setting up the machine, itis desirable to run up the upper wheel 55 until it is higher than desired, then to bring it down nearly to the required position, using the motor I 00 so far, and then to make the final adjust-.

ment by means of the hand wheel I2I, moving the slide downwardly at that time. When the motor I00 is deenergized, the motor shaft IOI thereof will readily turn in one direction or the other responsive to actuation of the hand wheel I2I. of the type which engages only in one position, and so far as certain features of the invention are concerned this clutch may be dispensed with altogether and the hand wheel I2I allowed to revolve when the motor I00 is running.

Work pieces to be finished or polished are guided between the opposing peripheral faces of the abrasive cones 50 and 55. For lapping operations, I prefer to use cones comprising fine mesh silicon carbide grain in a shellac bond. Owing to the fact that the wheels are skewed, one with respect to the other, the work pieces will be moved through the abrasive throat which is constituted by the two cones and work guides to be describedfand it is noted that the wheels revolve in the same direction so that their opposed The clutch I23 may be and preferably is.

' upwardly extending apron I25.

surface speeds thereof vary along cone elements,

and assuming that their angular velocities are the same, the peripheral surface speed of the lower cone is greater than that of the upper cone at the right-hand side of the machine where the work pieces are introduced, and the opposite condition is found at the left-hand side of the machine'where the work pieces emerge, and in the center of the machine where the diameters of the cones are equal, they have also equal peripheral surface velocities. For the feeding of work pieces through the machine, one cone at least is skewed so that the surface movement has a component in the direction of movement of the work pieces, and preferably both are so skewed, but one may be skewed more than the other and if the cone having the greater angular skew has a component in the direction the work pieces are to travel, the result of all the forces will be to cause the work pieces to move through the machine in the desired direction. It should also be noted that under some conditions, gravity materially assists the workpieces in passing through the machine, but not under all conditions. The machine embodiment herein described is susceptible of many adjustments to give quite different results with respect to finish and surfacing of a work piece, or grinding thereof, and by reason of these and other features, the machine is fairly universal.

Considering now the guides for guiding the work pieces, which may be rolls, pins, shafts or other cylindrical or partially cylindrical objects, these guides are mounted parallel with the front face of the machine (merely representative of a given vertical plane surface) but are inclined to the horizontal but one-half the included angle of the cones 50 and 55. Referring now particularly to Figures 1, 2 and 3, on the front of the machine and integral with the base 20 is an On the righthand end of this apron is a lug I26 in which is mounted rigidly an upwardly extending shaft I21 having rack teeth I20 cut on its right-hand side. Extending horizontally from the column 2 I, as better shown in Figures 2 and 3, is a bracket I29 which is thus stationary with respect to machine base 20. A vertical shaft I30 'is screw threaded around the bottom and fits in a bore in a boss I3I on the end of the bracket I29. Boss I3I constitutes a split journal which may be tightened by means of a nut I32 to hold the shaft I30 at a desired position of adjustment, and I provide a nut I33 on the screw threaded part of the shaft I30 for achieving precision in this adjustment. The right-hand side of the shaft I30 is provided with rack teeth I34, as in the case of the shaft I21, and preferably both of them are slabbed off in order that the teeth may be of uniform cross-section. Referring now particularly to Figures 1 and 6, mounted on the shaft I30 is a slidable member I35 which has a bore fitting the shaft I30 and which is provided with a boss I30 on the right-hand side of the machine which has a bore perpendicular to the first-named bore and offset from it, and in which bore is journaled a. shaft I3'Ihaving pinion teeth I30 cut in it which mesh with the rack teeth I34. In similar fashion, mounted on the shaft I2! is a slidable member I00 with which also is to. the journal bore in the member I40, and the shaft I31 extends through the bore in the boss I and has pinion teeth I42 cut therein which mesh with the rack teeth I28 on the shaft I21. In each case, the vertical and horizontal bores in the members I35 and I40 respectively intersect each other although their axes do not intersect.

Slidable member I40 has formed integral therewith one-half I45 of a casing I48 in which is received a worm wheel I41 fastened to the end of the shaft I31 and with which worm wheel I41 to form a square end or the like to receive av crank wrench II to turn the worm I48, and thus to rotate the shaft I31. It will be seen that rotation of the shaft I31 raises or lowers the'slid- 1 able members I35 and I40 together, andthus also raises or lowers the shaft I 31, maintaining it all the while horizontal. The purpose of the nuts I32 and I33 is to so adjust the shaft I88 that the shaft I31 may be placed in a horizontal plane or at least parallel to a given plane of the machine, particularly parallel to surface 28, and

once this adjustment is effected, these nuts I82 and I33 need not be touched unless or until vibration or other cause produces a misalignment of the parts. From the foregoing, it will be apparent that this adjustment is a precision adjustment for very fine movement.

The shaft I31 constitutes the mounting at the feed-in end of the machinefor the work guides. However, the work guides are not directly mounted on the shaft I31, but indirectly through a supporting mechanism which will now be described. Still referring to Figure 6, mounted on shaft I31 is a hollow shaft I55 which is screw threaded on the outside and in which the shaft I31 may turn, but which is restrained from endwise movement on the shaft I31, at one end, by means of a collar I55 adjustably fastened (as by a couple of set screws) to the shaft I31, and at the other end by the end of the boss I. Rotation of the shaft I55 is prevented by means of a collar I52, set screw I53 and pin I54. Mounted on the shaft I55 are a pair of forked supports I51 (see also Figure 16) to which are fastened the work guides I58. The forked supports I51 may be placed on or removed from the shaft I55, and for positioning them laterally, there ,are provided four (or more) nuts I59, I60, I5I and I52 and a collar I63 which, when adjusted, hold the supports I51 rigidly in the desired position of adjustment. The supports I51 as well as work guides I58 are similar in shape but oppositely oriented and for the adjustment of the machine for most work pieces, these work guides I58 are placed so that the vertical plane midway between them passes through the axes of the trunnions 3| and 5|.

The construction in detail of the work guides and associated parts as well as the work feeding trough will be hereinafter described, it being noted for the present that the work guides or removable wear strips attached to them contact the work on opposite sides as it moves through between the upper and the lower cones and constitute the other two elements of the work operalready described. Briefly, referring particularly to Figures 3 and 7, attached to the back of the apron I is 9. lug I88 in which is secured an upwardly extending shaft I81 having rack teeth I68 thereon. A bracket I88 is fastened to the base of the machine and in it is mounted a shaft I10 extending through a boss I1I formed in the bracket I88. Nuts I12 and I13 are provided for the same purpose as the nuts I32 and I53, and shaft I10 has rack teeth I14 thereon.

A slidable member I15 fits on the shaft I18 and has a lug I18, through which extends a shaft I11 having pinion teeth I18 meshing with rack teeth "8., One-half I85 of a casing I88 contains a worm wheel I81 with which meshes a worm I88 mountedon a shaft I88, the worm wheel I81 being secured to shaft I11. A cover plate I80 is provided and shaft I88 is slabbed off to fit the same removable crank wrench that fits the square end I48. 7 Upon the shaft I11 fits a hollow shaft I85 which is held in position by a collar I88, and forked supports I81 support the work guides I58 and are held in place on the shaft I85 by nuts I88 and 200. Intervening between the supports I81 and the work guides I58,.

however, are brackets I88, these brackets being attached to the supports I81 by pins "I so that the parts are articulated one to the other. Thus,

at both ends of the machine the work guides I58 ating throat, of which the cones constitute the may be raised and lowered simultaneously, or their ends may be adjusted individually in a vertical direction, preferably keeping them in parallelism, and in case the angle of the work guides to the horizontal plane is variedv (for example, by reason of using cones and 55 of different included angles), the resultant change in the distance between the shafts I31 and I11 is compensated for by the articulation at the pins 20I, but inasmuch as at the right-hand side of the machine the work guides are positioned at definite points, there can be no play in the work guides once they have been adjusted to the desired position. By the mounting-of the work guides through the mechanism and means described extreme flexibility and universality, so far as adjustment thereof to meet varying conditions of practical machine operation is concerned, are achieved, and at the same time once the desired adjustment has been obtained, the work guides are held firmly in position for the control of work pieces.

If the upper and lower cones 50 and 55 were maintained with their axes parallel, their peripheral surfaces would be thesame distance apart the entire length of the'work guides I58, assuming that each of them is a true cone. As aforesaid, however, it is desired to skew the axis of each of them slightly, and accordingly the work guides and peripheral surfaces will not be the same distance apart if they are true cones. It is desired, therefore, to alter the shape by dressing them slightly, shaping them into anticlastic bodies with slight negative curvature, in order that they may surface or finish work pieces along their entire lengths. This invention contemplates moving a dressing device parallel to the work guides for dressing the wheels after they have been set at the desired angle of skew. Preferably I make use of a rotating dressing device as embodied, for example, in an abrasive wheel, preferably comprising silicon carbide bonded with a vitreous bond. As this abrasive wheel (which is rotated rapidly during the dressing operation) is moved perpendicularly to its axis, it is provided with a surface which is circular in cross-section in any plane of th axis of the wheel, and in order that the abrasive dressing wheel may be of appreciable size, the upper cone 55 is moved upwardly at the time the dressing operation takes place. Thus, the dressing wheel, in a section perpendicular to the faces of the cones presents a shape like that of the bodiment of the inventionbeing between horizontal position for the dressing of cylinders, and an angle of about to the horizontal.

Formed on the bed plate 205 are ways 2 and .2l2, upon which are mounted, as best shown in Figure 5, a carriage 2 l3 having cooperating ways 214 and 215. The carriage. 213 carries its own motive power and drive for the spindle of the dressing abrasive wheel. For the translation of the carriage 213, and referring particularly to Figures 1, 4 and 5, there is a rectangular cut-out portion 215 on the front of the bed 205 having therein and attached thereto a rack bar 2". Referring now to Figures 4, 5 and 15, meshing with this rack bar 2 is a pinion gear 2I8 which is mounted on the end of a spindle 2l9 joumaled in a journal 220 extending through carriage 213. Attached to the front end of the spindle2 i9 and located in a gear box 221 is a bevel gear 222 with which mesh two bevel gears 223 and 224, each mounted on but free to revolve on a shaft 225 and each also mounted in journals 225 and 221 respectively provided in the gear box 22l. Keyed to the shaft 225 is a long sleeve 228 having clutch teeth 229 and 230 at the ends thereof, which can be made to engage respectively with clutch teeth 23l or 232 formed in the bevel gears 223 and 224. This constitutes a reversing mechanism and by the shifting of the clutch sleeve 228, the pinion 218 can be revolved in either direction, as the shaft 225 is revolved in a manner which will be presently described. Referring particularly to Figure 5, for the shifting of the clutch sleeve 228 on the shaft 225, I provide a controlling and reversing lever 235 pinned to a shaft 235 which is joumaled in the gear box 22l and the other end of which has attached to it an arm 231, on the end of which is pivotally mounted a fork 238 engaging an angular groove 239 in the sleeve 228, so that shifting of the lever 235 shifts the sleeve 228. I provide also a detent or snap-over device embodied in a pawl 240, spring pressed upwardiy by spring 24! mounted in a bore 242 of the gear box 22l, which pawl 240 engages any one of several notches or cam surfaces on a tail portion 243 (Figure 4) of the arm 231; snap-over devices or detents being known and it being established that clutch elements can be urged apart or together or into neutral position as may be desired thereby, with a high point on the cam element determining the shifting of the clutch element. In this particular embodiment of the invention, I prefer to form the tail portion so that the reversing lever 235 is normally urged to remain in its central or neutral position, so that a dog or stop on the base engaging the element on the carriage may bring the carriage to rest rather than reverse it, but the invention contemplates that a true reversing action may be effected.

Referring to Figures 1, 3 and .4, for the automatic actuation of the reversing mechanism just described, I provide dogs or stops 245 and 248 on the bed plate .205. The left-hand dog 245 is positioned to engage with a rod 241 which is slidable in the gear casing. 221 and which, as best shown in Figure 4, is connected by means of a link 248 to the reversing lever 235. Comparing now Figures 3, 5 and 15, the right-hand dog or stop 248 ispositioned to engage a rod 249 which extends through a hole in the gear casing 22l, the left-hand end of which is flattened and drilled and fits'over the spindle 250 of the fork 238. Thus, the carriage M3 is automatically stopped at either end of its travel on the ways 2, 212,

and if it is desired automatically to reverse the carriage, the tail portion 243. can be changed to a two-position snap-over device.

Referring to Figures 4, 5 and 15, for the rotation of the shaft 225 and in order to translate the carriage 213, I provide, in the gear box 22l, a worm wheel 25l which is pinned to the shaft 225 and with which meshes the worm 252 on a shaft 253 that is joumaled at 254, 255 in the box I and the carriage 213 respectively, and on which is mounted a pulley 255 connected by means of a belt 251 to a drive pulley 258 (Figures 1 and 3) mounted on the motor shaft 259 of an electric motor 250 which is bolted to a table 251 that is fastened to and extends forwardly from the carriage 213. The motor 250 also drives the spindle of the dressing wheel, the drive for and mounting of which will now be described.

Referring now particularly to Figure 1, extending upwardly from the carriage 2 l 3 is a bed plate 255. Mounted for movement parallel to the right-hand surface 255 thereof, by means of dovetailed ways indicated in Figure 1, is a spindle head 288. The usual dovetail is not shown in cross-section in this instance, but the stationary ways 258 and the movable slide 251 are sumciently indicated in Figure 1. The elements of the ways 258, 281 are perpendicular to the elements of the ways'2ll, 2l2, 2l4and 2l5, and adjustment of the spindle head 258 along its ways moves it perpendicular to the plane of the work guides I58, assuming the bed plate 205 is set to the proper angle, as already described. Referring now to Figures 1 and 10, the spindle head 258 is held on the ways and may be moved thereon by means of a nut 21! which is fastened to spindle head 258 and through which extends a screw 212, the upper end of which is rotatably and non-translatably mounted on the bed plate 255 by means of a collar 213 and spool 214, and the screw shaft 212 may be turned by hand to raise or lower the spindle head 258 bymeans of a hand wheel 215.

Referring now to Figures 3 and 10, in the spindle head 258 is joumaled a wheel spindle 215, on the far end of which is mounted an abrasive wheel 211, and on the near end of which is mounted a pulley 218. Referring now to Figures 1 and 3, a belt 219 extends from the pulley 218 to a pulley 280 on shaft 259 which may be integral with the pulley 258 but is preferably of a different diameter and located in a different plane. Thus, the spindle 218 is rotated whenever the motor 280 is energized, and to insure an even running of the spindle 215 and to'compensate for differences in elevation of the spindle infeed of the truing tool against the dressing head 288, I provide a belt tightener pulley 28l mounted on an arm 282 pivoted on a stud 283,

the arm being urged in one direction of rotation to tighten the belt by means of a coil spring 284.

The invention also contemplates a mechanism for rounding the periphery of the abrasive wheel 211 so thatits diametrical cross-section shall be journal sleeve 3I2 (see now Figure the axis a true circular segment, the center of which is,

in a plane centrally located in the wheel in an axial direction, and the radius of the segment being the same as the radius of.a work piece. By so forming the abrasive wheel 211 I can form the cones 50 and 55 into such shapes that truly cylindrical work pieces will be produced by the machine in spite of the skew of one or both of the wheels 50 and 55. Referring now to Figures 10, 11 and 12, I provide an attachment which is not upon the machine at all when the wheel 211 is being used to true the cones 50 and 55, but which may be mounted in position to true the dressing wheel whenthe carriage 2 I3 is in its left-hand end position (in this embodiment of the invention). Referring first to Figure 3, the spindle head 268 includes a journal portion 290, the outside of which is substantially cylindrical. Referring now to Figure 12, upon this cylindrical portion 290 may be clamped a two-part collar 29l by means of bolts 292 and nuts 293. This collar 29l, after it is adjusted in position, may be left upon the cylindrical journal portion 290 at all times. It may be turned into any desired angular position, and one part thereof has extending radially therefrom a stud 294, upon which the truing wheel truing device is removably mounted. For convenience in reading the drawings, Figure 10 is an elevation, in which vertical lines are vertical, looking from the rear of the machine, Figure 12 is a ViW from the left of Figure 10, and Figure 11 is a plan view.

Referring 'now particularly to Figures 12 and 17, the dressing wheel truing device extends from a base member 295 which has a bore 296 fitting the stud 294. One end of the base member 295 is slotted diametrically across the bore 296, and a pin 291 extends diametrically through the stud 294 and fits in slots 298, thus to fix the base member 295 in predetermined angular position upon the stud 294. Base member 295 should be pushed onto the stud 294 until it strikes the collar 29l or shoulder portion 299 provided thereon, with the pin 291 in the slots 298, and then a cam pin 300 may be turned by means of a handle 30l to lock the base member 295 firmly on collar 29L Referring now particularly to Figures 10 and 12, the other end of the base member 295 has formed thereon ways 302, 303 which extend in a direction perpendicular to the axis of the bore 296. By means of cooperating ways 304 and 305, a slide 306 is mounted upon the base member 295 and slides upon the ways302 and 303 and is held in desired position of adjustment by means of a screw 301 which extends into the base member 295 into an internally threaded bore thereof, and which screw is rotatabiy but non-translatably attached to the slide 306 by means of a collar member 308 fastened to the slide 306 engaging a spool 309 on the screw 201, the spool being connected to a hand wheel 3l0, and one of these parts being made out of two pieces so that the whole can be assembled. By turning the hand wheel 3l0, the slide 305 can be moved, and this hand wheel 3l0 causes the of which is perpendicular to the ways 302, 303, 80,4 and 305. In this'bore 3 is mounted a spindle M3 by means of a pair of cone bearings 3H and M5 in the sleeve 3l2 cooperating with a conical surface 3I8 formed on the spindle 3l3 and a cone 3| 1 loose on the spindle which may be tightened to take out end play in the entire assembly by means of nuts 3l8 on the outer end 3|9 of the spindle 3I3.

Still referring to Figure 10, fastened to or integrally formed with the spindle 3| 3 is a quadrant arm 320, upon the outer end of which the truing tool is mounted. A diamond 32! is imbedded in a plug 322 having a groove 323. The plug 322 fits in a bore 324 in the diamond slide 325. The diamond slide 325 is in the form of a shaft which has a slabbed-oif portion 326, the plane of which is inclined with respect to the axis of the slide 325. The slide 325 fits in a bore 321 in the quadrant arm 320, the axis of which bore 321 is parallel to the ways 302, 303, 304, 305 and perpendicular to the axis of the sleeve 3l2, and the axis of which bore 321 is radial to the truing wheel 211. The diamond slide 325 is keyed to the quadrant arm 320 by means of a key 328 in the slide 325 fitting in a spline 329 into the bore 324. A head 330 on the slide 325, as shown in Figures 10, 12 and 13, has a slot in the bottom engaging a spool 332 on the end of a screw 333 which extends into the quadrant arm 320 (drilled and internally threaded for this purpose). The diamond slide 325 may be moved and adjusted by turning the screw 333, and when the desired position of adjustment is achieved, a set screw 334 is tightened against the slabbedoff portion 326, and it will. be seen that when the set screw 334 is tightened, the diamond slide cannotbe moved to the left, Figure 10, on account of the incline of the slabbed-ofi portion 326. The diamond plug 322 can be locked in position by means of a set screw 335 engaging groove 323.

Prior to the dressing of the cones 50 and 55, the dressing wheel 211 is itself trued by the apparatus just described. This truing of the dressing wheel is for the dual purpose of giving it a true surface and also giving it the proper shape to shape the cones 50 and 55 for the lapping or abrading of a particular sized work piece, as distinguished from work pieces of different diameter. Preliminary to the truing of the wheel 211 the diamond 32] is positioned by apparatus shown in Figure 13. Figure-l3 is a view similar to Figure 10, but it will be noted that the spindle head 268 and the wheel 211 do not appear in Figure 13, and indeed this setting-up operation may be and preferably is performed on a work bench before the base member 295 is affixed to the collar 29! as already described.

Considering now Figure 13, I provide a cylindrical member 340 having the'diameter of work pieces to be finished, and this is mounted on the end of a spindle 3 whose tapered end 342 fits in a tapered bore 343 (see Figure 10) formed in the quadrant arm 320, the axis of which is coaxial with the sleeve 3i2. The set screw 334 is now loosened and by turning the screw 332 the diamond 32l is brought against the cylindrical surface of the cylinder 340, the set screw 334 then being tightened. The tool comprising the .cylinder 888 and spindle I is then removed,

and the base member 285 is mounted upon the collar 28I and fastened in position as already described. The motor 258 is now energized, and the spindle 215 and dressing wheel 211 caused to revolve.

Referring now to Figure 11, the apparatus having been set up as described, the dressing wheel 211 is trued by the diamond 32! by oscillating the quadrant arm 328. A rigid .handle 3 may be provided for this purpose. The result will be that the curvature of all diametral cross-sections of the wheel 211, at the periphery, will be the same as that of the cylinder 348, which in turn was the same as that of a work piece to be finished.

The entire apparatus connected to the base 285 is now removed by moving the handle 3M and pulling the base oil the stud 294. During the setting-up operation the carriage 2I3 has been stationary, the reversing handle 235 being maintained in mid position. The slide 28 is now moved upwardly, as by energizing the motor I58 in the proper direction, and the cone 55 is carried away from the cone 58. By manipulating the handle 235, the dressing wheel may be run toward the lower cone 58, and by turning the hand wheel 215, head 258 may be raised until it is apparent that the wheel 211 is slightly above the lower cone 58. It may be noted that the entire bed plate 205 has already been set so that the ways 2 and 2I2 are parallel to the top cone element of the cone 50, which is also parallel to the work piece guides I58, and the upper wheel 55 should at this time be substantially above the top of the dressing wheel 211.

At this time also, for certain sizes of work pieces, the guides I58 may be entirely removed from the machine. Under these conditions, the dressing wheel 211 may now be run into position between the cones 50 and 55, keeping it near the left-hand end thereof, however. The hand wheel 215 is now manipulated until the wheel 211 impinges upon the lower cone 58. This cone may now be trued by traversing the carriage 2I3 in the manner described. Without further description it will be clear that the upper cone 55 may be dressed either by moving it downwardly through manipulation of the hand wheel I2I, or by moving the wheel 211 upwardly by means of the hand wheel 215. The dressing of the cones 58 and 55 may be carried out with this apparatus in a variety of manners, as will now be clear to those skilled in this art, the precise way of carrying on the dressing and truing operations being dependent upon the exact structure of the wheels, and other factors which vary for particular machines and particular work pieces to be operated upon. Whenever the wheel 211 shows signs of becoming flat at its periphe y. it may be trued by the instrumentalities described, and in the truing thereof .hand wheel 310 is used to feed the diamond inwardly to take off material, but so long as the setting of screw 332 is unchanged, the radius of curvature of periphery of the wheel 211 does not vary, although its radius in a plane perpendicular to its axis may be less. As the result of these operations the cones 58 and 55 are shaped for the lapping of 'a particular sized work piece after they are skewed to a given angle, or to given Considering now the structure in detail of the work feeding guides, and the work feedinB trough, and referring first to Figures 8 and 9, I provide on the base 28 of the machine a bracket 858 with a pair of vertical grooves there'- in, and a grooved clamping plate III and suitable screws or bolts, not shown, for the clamping in position 'adjustably of a pair of removable bars 852, compare Figures 2, 8 and 9. The bars 352 may be bent as shown; as disclosed in Figure 9 they are flattened at the top and drilled to receive a pair of studs 353 projecting from the ends of a rectangular parallelopipedal block 854, upon one surface of which is a V-shaped groove 355. This groove 355 supports a V-trough 355, the block 858 being adjusted to cause the groove 855 to fit the bottom of the trough 355 whereupon the parts may be secured together by nuts 851.

Comparing now Figures 8 and 15, the lefthand end of the feed trough 855 is bent so that its elements are parallel to the work guides I58, and it rests upon the edges of the work guides I58 and between them; compare Figures -8, 18 and 22. The shape of the trough 355 is such as to deliver cylindrical work pieces of the desired size just above the level of a supporting bottom plate 358, which is seen in. Figures 9 and 18.

Considering now the structure in detail of the guides I58 and associated parts including removable wear strips, and referring, particularly to Figures 16, 1'1, 18, 19, 20, 21 and 22, the guides I58 are L-shaped in cross-section, but face oppositely,'and extend between the members I51 and I98. The supporting plate 358 already referred to, and as better shown in Figure 21, has upward extensions, that is to say it is U-shaped in cross-section, and is secured to the guides I58 by means of screws 358 fittin in slots 358 for adjustment. Certain of the parts to be described may be special for a given size of work piece to be finished.

Referring to the cross-section 20-28 of Figure 16, and referring to Figure 20 which illustrates it, a cross-bar 35I is bolted by bolts 852 to the guides I58. This cross-bar 38I is located very close to the leading edge of the lower wheel 50, and its purpose is to guide the work pieces accurately into the lapping throat determined by both wheels and the work guides or the wear strips thereof. It receives work pieces from the support 358, but is more rigid and gives to the work piece its final position as it enters the throat.

Referring now particularly to Figures 16, 17 and 20, the inside edges of the guides I58 are slightly cut away from a point just beyond the section 2 I--2I to the extreme left-hand end, and a number of wear strips are clamped upon them, and also at the delivery end of the machine a number of removable supporting strips. The removable wear strips are rectangular parallelopipeds, and are preferably made of cloth impregnated with artificial resinous material, such as a phenol-formaldehyde product, and the while pressed together in a press to produce a very dense and tough body. Such material can readily be bought and cut to the desired shape, and it is a material which will not readily scratch work pieces, and at the same time it is relatively wear-resisting. However, for certain uses of the machine I might prefer a harder material, and among many suitable materials which may be used I mention boron carbide,

Oarboloy, Nitroloy and Stellite. These materials are very hard and will not scratch work pieces. Referring now to Figure 17, at the leading-in edge of the throat I provide a pair of removable wear strips 555. These hold the work pieces in position just prior to and Just after entrance be-. tween the cones Ill and 55.. Next in line I provide a pair of removable wear strips 555, and finally a' pair of removable wear strips 581.

I Referring to Figures 16, 17, 20 and 21, all of the wear strips may be held in position by removable clamping plates 588, of which there may be a great number as shown, the plates 368 being held in position by bolts 359. The reason for making the wear strips in section and providing a number of clamping strips, is because they can more easily be trued in small sections. and each section thereof can be individually adjusted until the work contacting surfaces thereof lie in planes. Also any one strip may thus be readily removed and replaced at any time.

I show a pair of. removable work receiving guides 310 in Figure 1'7 preferably made of the same material as the strips 361. They may be supplemented by a pair of similar work receiving guides 310a, and they may be held in position by removable clamping plates 3' and 31m and bolts 312 and 312a. In cross-section they are not rectangular, but the inside edges thereof are tapered so as to form a work receiving surface like the V-trough 355. As the work passes from between the wheels 50 -and 55, it drops slightly downward onto the beveled surfaces of the work receiving guides 31ll3l0. As shown in Figure 19, to more rigidly hold the work guiding unit, a top plate 315 may be provided held in position by bolts 316 together with a bottom plate 311 as shown. The description of the work guides and associated parts is specific to a particular form which the invention may assume,

but these details of construction may be varied at will.

The operation of the machine has been already indicated, but assuming that a number of work pieces are placed in the trough 355 as shown in Figure 8, and the machine set up as described, gravity forces the work pieces into position between the cones and they are guided through the lapping throat by the removable wear strips 366, and when they pass beyond the wheels 50 and 55 they pass to the guides 310. The work pieces will proceed through the machine one after another, being practically contiguous in the lapping operation, and may be received in a basket or any suitable receptacle below the left-hand end of the guides 310. The machine is continuous in operation so long as it is supplied with work pieces.

In so much as the peripheral velocity of the wheel 50 and 55 is not the same at any point except the mid point of both wheels or cones, an abradant action is produced upon the work pieces, and they are driven by one or both wheels by the differential action thereof. By reason of the fact that one or both cones may be skewed, as described, grinding lines are avoided and a true lapping action may be achieved, but with certain speeds of the cones and certain material thereof metal may actually be removed from the work pieces. In fact, a wide range of operations may be performed by a machine constructed according to the invention, it being understood that the invention is not limited to any particular size or shape of the wheels nor material thereof nor setting of the various mechanisms described.

It will be observed that the line of contact between the respective abrasive members and the work piece being lapped isa helicalline. By skewing both of the wheels and-dressing both wheels with agrinding wheel'which has its periphery shaped with a radius equal to that of the finished work piece,- a curved surface is generated on the frustrum of a cone which causes each wheel to engage the periphery of the work in a helical line, as above stated. The effect of having a helical line of contact, among others, is to eliminate vibration'of the work piece and resultant chatter marks. as well as to avoid grinding or polishing lines all in a single direction. Thus more of a lapping action is; secured and even with the use of free cutting wheels the finish is improved.

This application more particularly claims the dressing and truing apparatus. It will be seen that the dressing wheel 21! is a wheel having a toric surface such that it generates shapes upon the abrasive cones 50 and 55 which in turn will generate a cylindrical work piece whose diameter is the same as that of the toric surface. Furthermore, I provide truing apparatus for truing thetoric surface, as fully described herein, but this truning apparatus for truing the toric surface is claimed in my copending application Serial No. 398,438 filed June 17, 1941.

It will thus be seen that there has been provided by the invention a method and an apparatus in which the various objects hereinabove set forth together with many practical advantages are successfully achieved. As many possible embodiments might be made of the above invention, and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings'is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In apparatus of the class described, a toric dressing wheel for anabrasive wheel, a slide upon which said toric dressing wheel is mounted whereby to adjust it in a direction perpendicular to its axis, and a second slide upon which the first slide is mounted to move the toric wheel in a direction perpendicular to its axis, which direction is also perpendicular to the direction of movement of the first slide, whereby the toric wheel may be moved along one slide to dress an abrasive wheel and adjusted along the other slide to increase or decrease the amount of cut, and the toric wheel in moving along the abrasive wheel will move perpendicular to the axis of the toric wheel.

2. In apparatus of the class described, a pair of abrasive wheels mounted on axes slightly skewed with respect to each other,'means for moving said wheels toward and from each other to form a throat for the grinding of work pieces and to space said wheels apart, a toric dressing wheel having a toric surface, means mounting and guiding said toric dressing wheel for movement between said wheels when they are spaced apart, said toric abrasive wheel being mounted on an axis perpendicular to its direction of movement, and means for rotating all of said wheels, whereby to form a perfect abrasive throat between the two first named abrasive wheels to abrade cylindrical work pieces whose radius is equal to the radius of the said toric surface.

3. In apparatus of the class described, an abrasive wheel which has a surface of revolution, means for rotating said abrasive wheel, a carhaving a toric surface.

line which is within a few degrees, such as within the limits of skewing the abrasive wheel for the purpose of feeding a work piece axially of said work piece, of being parallel to a surface element of said surface of revolution, but which straight line is definitely not parallel to said surface element, a second abrasive wheel mounted on said carriage having an axis perpendicular to the line of movement of the center of the second abrasive wheel. as it moves with the carriage, means to rotate said second abrasive wheel, means to move said carriage with said second wheel peripherally in contact with said first wheel whereby to dress and shape said first wheel for contact with cylindrical work pieces, said second abrasive wheel 4. In apparatus of the class described, a slideway, av carriage mounted for movement along said slideway, a pivotal mounting for said slideway permitting it,as a whole to be turned on an axis perpendicular to the line of movement of the carriage, a second slideway on the carriage perpendicular to the first slideway, a second carriage on the second slideway, an abrasive wheel spindle on the second carriage whose axis is perpendicular to the lines of movement through said axis of each of said carriages on saidslideways, an

abrasive wheel on said spindle, means to rotate the abrasive wheel.- and means to feed the first carriage along the first slideway whereby the abrasive wheel may true another abrasive wheel by movement along the nrstslideway and be ad- Justed for taking more or less cut along the sec'ondslideway,

a 5. The method of dressing a form true cylinders of work pieces which comprises, shaping, the periphery of an abrasive disk toa toric form the toxic diameter-of which is thesame as the diameter of the work piece, then moving the time shaped toric' abrasive disk in a direction perpendicular to its axis in contact with the pseudo-spherical abrasive wheel along a path later to be taken by the work piece to beformed into a true cylinder, said path being slightly skewed to the axis of the pseudospherical abrasive wheel, thus correcting the pseudo-spherical shape of the abrasive wheel to the exact geometrical shape required for theparticular angle of skew to produce a true cylinder when the work piece is moved along said path.

HERBERT S. INDGE.

I v pseudo-spheri-v cal abrasive wheel to such shape as accurately to 

